1. Field of the Invention
The present invention relates to a substrate position detecting apparatus, a substrate processing apparatus using the substrate position detecting apparatus, and a deposition apparatus.
2. Description of the Related Art
A known substrate position detecting apparatus may include an image pickup device to pick up an image of a substrate that is a target of position detection, a light scattering panel member arranged between the image pickup device and the substrate and having a first opening to secure a field of view of the image pickup device with respect to the substrate, a first illumination device to illuminate the panel member with light, and a processing unit to obtain a position of the substrate from the image of the substrate picked up by the image pickup device (for example, Japanese Laid-Open Patent Publication No. 2010-153769).
The substrate position detecting apparatus proposed in Japanese Laid-Open Patent Publication No. 2010-153769 is arranged above a window that is formed at a top surface of a chamber of a deposition apparatus, and detects the position of a wafer (substrate) within the chamber via the window. In the substrate position detecting apparatus proposed in Japanese Laid-Open Patent Publication No. 2010-153769, the panel member is formed by an acrylic plate coated with white pigments, and light is irradiated on the panel member so that the panel member makes white emission, in order to make the wafer appear white. On the other hand, a susceptor on which the wafer is placed may be made of carbon or SiC coated carbon, and such a susceptor appears black when illuminated by the light from the panel member. Contrast between the white-appearing wafer and the black-appearing susceptor enables clear recognition of a wafer edge, in order to reduce detection error.
However, according to the substrate position detecting apparatus proposed in Japanese Laid-Open Patent Publication No. 2010-153769, deposition may occur on an inner side of the window provided on the chamber as the deposition within the chamber progresses. In a case in which the deposition causes a colored film having reflectivity to be formed on the window, the film may reflect light at the window to thereby deteriorate the contrast of the image picked up by the image pickup device.